From 8f4b0a11937b19f9ac783dcf918d470b9ed7f5c0 Mon Sep 17 00:00:00 2001
From: tb <tb@openbsd.org>
Date: Wed, 5 Jan 2022 11:01:59 +0000
Subject: [PATCH] dhcpd: straightforward conversion to HMAC_CTX on the heap,
 similar to what was done in spamd a while back.

ok florian
---
 usr.sbin/dhcpd/sync.c | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/usr.sbin/dhcpd/sync.c b/usr.sbin/dhcpd/sync.c
index d17455e8fb9..1f701f60d46 100644
--- a/usr.sbin/dhcpd/sync.c
+++ b/usr.sbin/dhcpd/sync.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sync.c,v 1.23 2017/02/13 23:04:05 krw Exp $	*/
+/*	$OpenBSD: sync.c,v 1.24 2022/01/05 11:01:59 tb Exp $	*/
 
 /*
  * Copyright (c) 2008 Bob Beck <beck@openbsd.org>
@@ -393,7 +393,7 @@ sync_lease(struct lease *lease)
 	char pad[DHCP_ALIGNBYTES];
 	u_int16_t leaselen, padlen;
 	int i = 0;
-	HMAC_CTX ctx;
+	HMAC_CTX *ctx;
 	u_int hmac_len;
 
 	if (sync_key == NULL)
@@ -403,8 +403,10 @@ sync_lease(struct lease *lease)
 	memset(&lv, 0, sizeof(lv));
 	memset(&pad, 0, sizeof(pad));
 
-	HMAC_CTX_init(&ctx);
-	HMAC_Init(&ctx, sync_key, strlen(sync_key), EVP_sha1());
+	if ((ctx = HMAC_CTX_new()) == NULL)
+		goto bad;
+	if (!HMAC_Init_ex(ctx, sync_key, strlen(sync_key), EVP_sha1(), NULL))
+		goto bad;
 
 	leaselen = sizeof(lv);
 	padlen = DHCP_ALIGN(leaselen) - leaselen;
@@ -416,7 +418,8 @@ sync_lease(struct lease *lease)
 	hdr.sh_length = htons(sizeof(hdr) + sizeof(lv) + padlen + sizeof(end));
 	iov[i].iov_base = &hdr;
 	iov[i].iov_len = sizeof(hdr);
-	HMAC_Update(&ctx, iov[i].iov_base, iov[i].iov_len);
+	if (!HMAC_Update(ctx, iov[i].iov_base, iov[i].iov_len))
+		goto bad;
 	i++;
 
 	/* Add single DHCP sync address entry */
@@ -434,12 +437,14 @@ sync_lease(struct lease *lease)
 	    piaddr(lease->ip_addr), ntohl(lv.lv_starts), ntohl(lv.lv_ends));
 	iov[i].iov_base = &lv;
 	iov[i].iov_len = sizeof(lv);
-	HMAC_Update(&ctx, iov[i].iov_base, iov[i].iov_len);
+	if (!HMAC_Update(ctx, iov[i].iov_base, iov[i].iov_len))
+		goto bad;
 	i++;
 
 	iov[i].iov_base = pad;
 	iov[i].iov_len = padlen;
-	HMAC_Update(&ctx, iov[i].iov_base, iov[i].iov_len);
+	if (!HMAC_Update(ctx, iov[i].iov_base, iov[i].iov_len))
+		goto bad;
 	i++;
 
 	/* Add end marker */
@@ -447,12 +452,16 @@ sync_lease(struct lease *lease)
 	end.st_length = htons(sizeof(end));
 	iov[i].iov_base = &end;
 	iov[i].iov_len = sizeof(end);
-	HMAC_Update(&ctx, iov[i].iov_base, iov[i].iov_len);
+	if (!HMAC_Update(ctx, iov[i].iov_base, iov[i].iov_len))
+		goto bad;
 	i++;
 
-	HMAC_Final(&ctx, hdr.sh_hmac, &hmac_len);
+	if (!HMAC_Final(ctx, hdr.sh_hmac, &hmac_len))
+		goto bad;
 
 	/* Send message to the target hosts */
 	sync_send(iov, i);
-	HMAC_CTX_cleanup(&ctx);
+
+ bad:
+	HMAC_CTX_free(ctx);
 }
-- 
2.20.1